metallic circuit การใช้

There was less noise and crosstalk with a 2 conductor metallic circuit.
The metallic circuit is complete throughout, no earth connection being used.
One wire circuits were typically called earth return circuits, or sometimes'non metallic'and two wire were also referred to as'metallic circuits '.
Another of his early transmitters was a rough model of the human ear, carved in oak, and provided with a drum which actuated a bent and pivoted lever of platinum, making it open and close a springy contact of platinum foil in the metallic circuit of the current.
Later, when telephony began to replace telegraphy, it was found that the currents in the earth induced by power systems, electrical railways, other telephone and telegraph circuits, and natural sources including lightning caused unacceptable interference to the audio signals, and the two-wire or'metallic circuit'system was reintroduced around 1883.